The role of humoral and neuronal factors in the control of cerebral blood flow and metabolism is controversial. We have studied the role of the adrenal/hypophysis axis and the role of sympathetic activation on cerebral blood flow and metabolism under normal and stressful conditions. Our initial work has been done with the hypercapnic model for stress, but the studies will be extended to other models for stress, e.g., hypoxia, hypoglycemia and withdrawal from chronic alcohol consumption.